here's the problem. You guys NEVER EVER EVER EVER EVER EVER EVER EVER delete PM's. If you could add attachments.. it would clog EVERYTHING past the point of return. then we'd beg people to delete stuff and some would but most wouldn't.. and then we'd go ahead and delete it.. and then people would go crazy because that's the ONLY place they stored some piece of information that will cause the destruction of human life if not retrieved... but the problem is we would have physically deleted the PM instead of a soft delete so humans would all die
this has been researched a lot.